Advances in Two-Dimensional Black Phosphorus-Based Nanostructures for Photocatalytic Applications

As a new two-dimensional ( 2D) monoelement material in post-graphene era, black phosphorus ( BP) has gained broad prospects in photocatalysis due to its extraordinary physicochemical characteristics including unique anisotropic structures, high carrier mobility and thickness-controlled bandgap. Nevertheless, the extremely narrow bandgap of BP (<= 1. 5 eV) is detrimental for the efficient separation of photogenerated electron-hole pairs that limits the photoreactivity. And the isolated BP suffers from the severe degradation upon long-term exposure due to PxOy species formed by the reaction between the lone pair electrons onto the BP surfaces and oxygen in ambient environment, then BP will gradually corrode in water through the formation of phosphoric acid. Therefore, the lower photoreactivity and instability of BP material restrict its industrial implementation. To overcome these obstacles , various effective strategies like creating a wide range of plasmonic hybrid nanostructures and mixed-dimensional heterojunctions have been developed. Herein, the recent progress on BP-based nanostructures through hybridization with dissimilar components like metals, semiconductors, carbon materials, etc. has been summarized and its applications in photocatalytic reactions such as water splitting for hydrogen evolution , organic pollutant removal , CO2 photoreduction and N-2 fixation have also been reviewed , together with the insights into the photocatalytic mechanism for the boosted photoreactivity and good recyclability. Lastly,the challenges and potential directions of BP-based nanostructures toward high-efficiency photocatalytic reactions are analyzed and provided.